336 ERNEST A. BACK. 



reaching nearly to the anterior and posterior borders, but not over 

 the sides, and segments 5, 6 and 7 above, velvety black. In the 

 female the seventh segment is usually whitish pruinose, while the pos- 

 terior portion of the fourth is also velvety black; thus the tergum 

 presents a trifasciate appearance. Venter of both sexes wholly gray- 

 ish-white pruinose. Abdomen apparently bare, with fine microscopic 

 pile and longer pile and bristles on the sides of segment 1. Legs 

 wholly grayish-white pruinose with microscopic hair; the femora stout, 

 swollen; the front and middle pairs with bristles only at their tips, 

 the hind pair with a row before and behind; bristles of femora and 

 tibiae white; of the tarsi black and white. Claws black; pulvilli 

 whitish. Wings blackish hyaline; all the submarginal and posterior 

 cells open, the anal cell closed before the margins, the fourth posterior 

 cell sessile or open at base. 

 Type'. — Say's type is lost. 



Habitat.— Chicopee (July 10-26, F. Knab) and West Spring- 

 field (June 28, 1896, F. Knab), Mass.; Conn.; North Wood- 

 bury, N. J. (Aug. 1, 1901, C. W. Johnson); Lehigh Gap, Pa. 

 (June 28, 1901, C. W. Johnson); Penington Gap, Va. (Osten 

 Sacken); N. C.; Glen, Sioux Co., Neb. (P. R. Jones); Clark 

 Co., Ks. (June, 1962 ft., F. H. Snow); So. Cal.; N. M.; Mexico. 

 This is rather a common species inhabiting sandy localities. 

 The duskiness of the wings is variable, sometimes wholly lack- 

 ing. Variable also is the amount and extent of the white 

 bloom on the tergum of abdomen, although the trifasciate 

 appearance is usually maintained. Two specimens from Kan- 

 sas, belonging to Prof. F. H. Snow, are somewhat testaceous 

 in color and the second, third, fifth and sixth abdominal seg- 

 ments are velvety opaque black except the narrow laterally 

 widening anterior borders which are covered with the same 

 silvery white bloom as the rest of the abdomen. These thus 

 agree with four specimens from lower California which Prof. 

 C. H. T. Townsend mentions. This is doubtless a variety. 

 Dr. S. W. Williston states that he has seen typical specimens 

 of trifasciatus from New England, Kansas, and lower Cal- 

 ifornia. 



